He had claimed in the journal Science to have created a stem cell line from a cloned human embryo, later publishing a second paper in which he said his team had extracted material from cloned human embryos that identically matched the DNA of 11 patients.

His "progress" appeared to bring researchers closer to the point where they could offer personalised cures, using tissue grown from embryonic stem cells to repair damaged organs or treat diseases like Alzheimer's.

But in December a panel at Seoul National University found that his research had been "intentionally fabricated". In May, prosecutors brought charges against him and his team.

He is accused of accepting donations worth 2bn won ($2.1m, £1.14m) on the basis of his research, and of embezzling a further 800m won ($831,000, £451,000) in research funds.

He is also alleged to have bought human eggs for his research work, which is a violation of South Korea's bio-ethics law.

He is being tried with five colleagues who are facing similar charges.